SALT LAKE CITY — Multiple counties throughout the most populated areas in Utah are under an action alert from the state Division of Air Quality because smoke and heat have combined to produce unhealthy levels of air pollution.
A "yellow" day alert for moderate pollution was issued Monday for Cache County in extreme northern Utah, as well as Box Elder, Weber, Davis, Salt Lake and Utah counties. The same advisory applies to Uintah and Tooele counties.
It's likely, too, that moderately hazardous conditions exist elsewhere in the state where the division doesn't have monitors, but fires have been a problem, said Bryce Bird, air quality director.
Bird said smoke from the Grease wildland fire outside of Delta had wafted into Nephi and even lingered around Elk Ridge in southern Utah County.
"We don't have a monitoring station there, but it was clear that the concentrations of pollution were elevated."
Smoke from multiple fires in the region led to a declaration of a red air day last week for Uintah County. A fire caused by target shooting began Sunday in Cache County's Millville Canyon, leading to deterioration of air quality conditions there.
In addition to providing information on its website with the latest forecast for air quality conditions, Bird said the division has been fielding phone calls from residents concerned about what precautions they can take when the air turns smoky.
Bird said minimizing outdoor activity while smoke hangs in the air is advisable, especially for vulnerable groups such as the very young, the elderly or people who have respiratory conditions like asthma.
"People should use good judgment and avoid being outside to the extent they can," he said, "and find an area not being impacted by the smoke. It becomes a personal protection issue."
Triple digit temperatures along the congested Wasatch Front can bake the air to the point where ground-level ozone reaches unhealthy levels — even absent the smoke in valley.
"Smoke can be a precursor to that," Bird said, leading to action alerts being called more frequently.
During these types of days, Bird said people are being asked to voluntarily reduce driving by carpooling or consolidating trips as much as possible.
The state has also compiled information on wildfires and air pollution at the website for the Utah Clean Air Partnership where residents can learn additional steps to protect themselves against smoke from the wildfires.
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